I recently bought a Posture Curve Back Support , pg. 170, Performance Products:
www.************************************************************ This snugs up against my lumbar region and feels good during any drive (at least so far) Advanced Automotive has cheaper/less expensive examples but at $38 dollars and in a gray color I was pleased with the purchase. A strap holds it in place. You might give something like these products a try before selling the car.
AKL